The present invention relates to telecommunications and data communications, and more particularly to a method and apparatus for providing end devices with network access (e.g., Internet access) by selecting from a plurality of network terminating devices and corresponding access networks.
For connecting an end device (e.g., a phone, computer, appliance, vending machine, car, etc.) to the Internet and associated networking environments in existence today, there is a wide choice of different access mechanisms including fixed access, cellular access, WLAN access, satellite access, and the like, which are available to provide access to the IP network. In order to use an access mechanism, a network terminating device is needed to connect the end device to the access network and, through the access network, to the Internet. For example, a cable or wire pair are examples of a network terminating device associated with a fixed access network through which an end device can be connected to, e.g., the Internet. Likewise, a cellular phone is an example of a network terminating device associated with the cellular wireless access network, which provides another route for end devices to be connected to the Internet. Yet another example is a PCMCIA card for WLAN network access which also may be used by an end device to communicate with the Internet. Those skilled in the art will recognize many other examples of network terminating devices and their corresponding access networks through which end devices may reach other networks.
For many end devices, it would be desirable to be able to use different access mechanisms (i.e., network terminating devices and access networks) for different connection situations, depending on factors including, for example, availability, pricing, bandwidth and the like. However, many end devices are configured to use only one type of access mechanism. For example, many personal computers can only connect to the Internet via a wireline modem and the fixed telephone access network.
In order to use different access mechanisms, an end device must have a network terminating device for each access network. Therefore, for end devices such as a laptop computer, either several network terminating devices are required to be permanently installed in the laptop or network terminating devices have to be disconnected and reconnected to the laptop each time a different access mechanism is desired. A problem arises in that if network terminating devices must be disconnected and reconnected it is difficult to determine for any given point in time which access mechanism provides the best quality connection to the ultimate network of interest, e.g., the Internet.
Providing such a determination was attempted in the BARWAN project at the University of California at Berkeley. In the BARWAN project, a laptop was equipped with access mechanisms including, for example, IR, WLAN (both of which were used to access a LAN), Ricochet, CDPD and satellite interfaces. The access mechanism that could offer the best quality for the moment was used for data transfer. Since each of the access mechanisms provided different coverage, different access mechanisms were used depending on where the user was located, for example, at the office, in the car, and the like. Again, however, the difficulty with such a system is that a separate network terminating device was provided directly to the end device for each access mechanism leading to the need for additional hardware and correspondingly higher costs. Moreover, given that space and power consumption, for example, are important considerations for end devices such as cellular phones and laptops, additional disadvantages may be posed by the additional hardware required to provide a separate network terminating device for each access mechanism.
More flexibility and lower cost would be possible in such a system, particularly in a multi-user environment such as an office, where sharing of such network terminating devices is possible. Sharing may require, for example, a wireless interface between each of the end devices and the network terminating devices, so that the network terminating devices can be “shared” among many users. In this way a user can make use of whatever access network terminating device is available at a given point in time, without the need for a direct, physical connection to each network terminating device. Such an approach to sharing has been studied at the Internet Real-time Laboratory at Columbia University and was summarized in a paper entitled “Connection Sharing in an Ad Hoc Wireless Network Among Collaborating Hosts”, by M. Papadopouli, and H. Schulzrinne, (http://www.cs.columbia.edu/-maria/nossdav99 final.ps).
In the Columbia project, a framework for collaborating among hosts to share a limited number of network connections with each other is being contemplated. The goal is to increase a quality metric and data availability primarily by performing load balancing between different network terminating devices which might be available depending on the demand from the users in the shared environment. Each access device measures the traffic that passes through it and provides that information to the end devices so that the end devices can choose the access device which is least loaded. Such a system however, may not achieve the “best” possible access for a given end device, since different types of end devices and connections may have widely varying connection considerations in determining what constitutes a “best” access. For certain types of connections, available bandwidth may be a primary “best” access consideration, while for other types of connections low delay time might be paramount.
Another drawback of the system evaluated in the Columbia project is its usage of collaborating hosts which provides a uniform, but rigid, access opportunity for end devices. Instead, it would be desirable to provide a more flexible system wherein different types of end devices may have different selection criteria with respect to different types of network terminating devices and access networks. For example, some network terminating devices may be provided which offer access to anyone (i.e., public access points placed in airports, shopping malls, etc.), some network terminating devices may be provided which offer access to a specified group of people (i.e., employees of a particular company or participants in a particular conference) and some network terminating devices may be provided which offer access only to a particular end device. In such an environment, it would be desirable to permit an end device, particularly a mobile end device, to employ more sophisticated access network selection techniques so that a user can have preferred network accesses given various access options which might be available (e.g., “I want to use my own access devices whenever possible, and the cheapest public access device in all other cases”).
Yet another drawback of the Columbia system is that once an end device is linked to an external network through one of the collaborating hosts, it continues to operate through that host for the duration of the connection. Even if that particular host was a good choice initially, it may not always provide the best possible connection for the entire time that the link is operative.
It would be desirable, therefore, to develop a method and apparatus which provide selective and flexible connectivity to a plurality of network terminating devices to select an access mechanism which provides a best possible access for each situation. Such a method and apparatus should provide access to, e.g., the Internet, without the need for a plurality of network terminating devices to be physically integrated into the end devices, and in a user friendly manner.